Re: "the jammers revenge on mobile prattlers" in the Times

Alasdair <mail@bobaxter.coo.uk> wrote:

> On Tue, 4 Dec 2007 14:44:03 +0000 (UTC), Mike Civil
> <mike@duncodin.org> wrote:
>
> >I suspect the devices are pretty indiscriminate. After all they're
> >unregulated and presumably designed to be multi-frequency so that they
> >can affect any mobile phone in any country regardless of what frequency
> >band(s) they happen to be using.

> I wonder what the penalty is if one is found using one of those
> jammers?

How stupidly would you have to use it to get caught?

You're in a moving train, switching it on for a second or two at a
time, and the prattlers just think it's a network problem when they
get cut off. There's no way the "authorities" would pin it down.

"Nomen Nescio" <nobody@dizum.com> wrote in message
news:c01cb116262e514280f35c7563d0085e@dizum.com...
..
>
>> I wonder what the penalty is if one is found using one of those
>> jammers?
>
> How stupidly would you have to use it to get caught?
>
> You're in a moving train, switching it on for a second or two at a
> time, and the prattlers just think it's a network problem when they
> get cut off. There's no way the "authorities" would pin it down.
>

Can anyone advise whether these devices are legal to possess? I know they
are illegal to use but am unsure about possession.

From what I understand the range of these devices is rather limited - only
around a radius of 5 metres or so, and are not always reliable against some
phones/networks. You'd need one of the more powerful mains powered ones to
silence an entire train carriage I would have thought.

The tempation to use these devices to silence the inane babblers on the
train or bus is rather strong I admit. I notice with horror that they are
looking at introducing the use of mobile phones on aircraft - Sheesh!

--
Peter <X-Files fan>

On Fri, 7 Dec 2007 19:51:22 -0000, "Trust No One®"
<dana.scully@usa.xnet> wrote:

> I notice with horror that they are
>looking at introducing the use of mobile phones on aircraft - Sheesh!

If this does happen, I imagine the phones will be special ones
supplied by the airline and calls will cost an arm and a leg.

The argument for prohibiting the use of mobiles in aircraft has always
been that the radio transmissions could affect the electronics of the
aircraft and could be dangerous. Are they now saying that we have
been conned all along and mobiles are quite safe if used in flight.

--
Alasdair.

On Sat, 08 Dec 2007 02:19:41 +0000, Alasdair <mail@bobaxter.coo.uk>
wrote:

>On Fri, 7 Dec 2007 19:51:22 -0000, "Trust No One®"
><dana.scully@usa.xnet> wrote:
>
>> I notice with horror that they are
>>looking at introducing the use of mobile phones on aircraft - Sheesh!
>
>If this does happen, I imagine the phones will be special ones
>supplied by the airline and calls will cost an arm and a leg.

They've already got those.

>The argument for prohibiting the use of mobiles in aircraft has always
>been that the radio transmissions could affect the electronics of the
>aircraft and could be dangerous. Are they now saying that we have
>been conned all along and mobiles are quite safe if used in flight.

Christopher A.Lee wrote:

>> The argument for prohibiting the use of mobiles in aircraft has always
>> been that the radio transmissions could affect the electronics of the
>> aircraft and could be dangerous. Are they now saying that we have
>> been conned all along and mobiles are quite safe if used in flight.

The plan involves a very low powered base station actually inside the
aircraft, linked to a satellite channel to allow calls while in flight.
There will, naturally, be a premium rate charged for calls. This will be
turned on when the plane is at cruising height, & turned off when landing.

The problem has been that cellphones don't work inside aircraft without
cranking the transmit power up all the way, which can potentially
interfere with the signals used for glidepath control while landing, as
well as GPS signals, especially when you have a couple of hundred phones
all shouting as loud as they can to find a cell to use. They also stop
working on flights over water once you get more than a few miles from
land. Another problem is that they can't lock onto the channel if
they're moving at more than about 300 mph relative to the base station
due to the doppler effect.

The proposed system means that the transmit power on the phones will be
minimal & under the control of the aircrew. They could also potentially
transmit a "System not working" signal to stop phones from transmitting
at dangerous points of the flight.

--
Tciao for Now!

John.

In message <bivjl3l8p00l1m2vq63c5qnb9t3m6uk19c@4ax.com>
Alasdair <mail@bobaxter.coo.uk> wrote:

> On Fri, 7 Dec 2007 19:51:22 -0000, "Trust No One®"
> <dana.scully@usa.xnet> wrote:
>
> > I notice with horror that they are
> >looking at introducing the use of mobile phones on aircraft - Sheesh!
>
> If this does happen, I imagine the phones will be special ones
> supplied by the airline and calls will cost an arm and a leg.

They've existed for some years now, and yes they do cost an arm and a leg.

>
> The argument for prohibiting the use of mobiles in aircraft has always
> been that the radio transmissions could affect the electronics of the
> aircraft and could be dangerous. Are they now saying that we have
> been conned all along and mobiles are quite safe if used in flight.
>

The ones fitted are properly screened.

--
Graeme Wall
This address is not read, substitute trains for rail.
Transport Miscellany at <http://www.greywall.demon.co.uk/rail/index.html>

Graeme Wall wrote:

>
> The ones fitted are properly screened.
>

I doubt that it was ever really a screening issue, other than a very
minor risk.

The first problem was that GSM is effectively pulsed, which makes
EMC much more of a problem.

The second issue is that, when run in a tin can, the handset will
crank up its power to maximum.

The third issue, again because it is being operated in a tin can, is
that you can get standing waves set up inside the cabin which
effective increase to power levels significantly above those
measured in an open-field site. This can take the localised power
levels way above those envisaged by the standards.

regards, Ian

In article <bivjl3l8p00l1m2vq63c5qnb9t3m6uk19c@4ax.com>, Alasdair
<mail@bobaxter.coo.uk> scribeth thus
>On Fri, 7 Dec 2007 19:51:22 -0000, "Trust No One®"
><dana.scully@usa.xnet> wrote:
>
>> I notice with horror that they are
>>looking at introducing the use of mobile phones on aircraft - Sheesh!
>
>If this does happen, I imagine the phones will be special ones
>supplied by the airline and calls will cost an arm and a leg.
>
>The argument for prohibiting the use of mobiles in aircraft has always
>been that the radio transmissions could affect the electronics of the
>aircraft and could be dangerous. Are they now saying that we have
>been conned all along and mobiles are quite safe if used in flight.
>

No give them their due the aircraft environment is a very sensitive one
and is very safety conscious. If there was the slightest risk then they
should not be allowed but its taken some time to get that far.

--
Tony Sayer

In article <fjdbd6$6vl$1@stable.tornevall.net>, John Williamson
<johnwilliamson@btinternet.com> scribeth thus
>Christopher A.Lee wrote:
>
>>> The argument for prohibiting the use of mobiles in aircraft has always
>>> been that the radio transmissions could affect the electronics of the
>>> aircraft and could be dangerous. Are they now saying that we have
>>> been conned all along and mobiles are quite safe if used in flight.
>
>The plan involves a very low powered base station actually inside the
>aircraft, linked to a satellite channel to allow calls while in flight.
>There will, naturally, be a premium rate charged for calls. This will be
>turned on when the plane is at cruising height, & turned off when landing.
>
>The problem has been that cellphones don't work inside aircraft without
>cranking the transmit power up all the way, which can potentially
>interfere with the signals used for glidepath control while landing, as
>well as GPS signals, especially when you have a couple of hundred phones
>all shouting as loud as they can to find a cell to use. They also stop
>working on flights over water once you get more than a few miles from
>land. Another problem is that they can't lock onto the channel if
>they're moving at more than about 300 mph relative to the base station
>due to the doppler effect.

Not quite true.. If your sideways on to a BST the relative speed will be
much less...

However you will also interfere with a lot of base stations using the
same channel..
>
>The proposed system means that the transmit power on the phones will be
>minimal & under the control of the aircrew. They could also potentially
>transmit a "System not working" signal to stop phones from transmitting
>at dangerous points of the flight.
>
Or if it gets too noisy)
--
Tony Sayer

"Graeme Wall" <Rail@greywall.demon.co.uk> wrote in message
news:ff4ce34d4f%Rail@greywall.demon.co.uk...
> In message <bivjl3l8p00l1m2vq63c5qnb9t3m6uk19c@4ax.com>
> Alasdair <mail@bobaxter.coo.uk> wrote:
>
>> On Fri, 7 Dec 2007 19:51:22 -0000, "Trust No One®"
>> <dana.scully@usa.xnet> wrote:
>>
>> > I notice with horror that they are
>> >looking at introducing the use of mobile phones on aircraft -
>> >Sheesh!
>>
>> If this does happen, I imagine the phones will be special ones
>> supplied by the airline and calls will cost an arm and a leg.
>
> They've existed for some years now, and yes they do cost an arm and a
> leg.
>
>>
>> The argument for prohibiting the use of mobiles in aircraft has
>> always
>> been that the radio transmissions could affect the electronics of the
>> aircraft and could be dangerous. Are they now saying that we have
>> been conned all along and mobiles are quite safe if used in flight.
>>
>
> The ones fitted are properly screened.


I assume you mean the aircraft (electronics) has proper screening? Why
screen a mobile - it is designed to radiate?

Having said that I read recently that mp3 players generate many times
more RFI than either a mobile phone or a laptop, although I don't own a
mp3 player so I can't test the validity.


--
Woody

harrogate three at ntlworld dot com

tony sayer wrote:

<Cellphones travelling fast>

Another problem is that they can't lock onto the channel if
>> they're moving at more than about 300 mph relative to the base station
>> due to the doppler effect.
>
> Not quite true.. If your sideways on to a BST the relative speed will be
> much less...
>
As I said "relative speed" ;-)

I maybe should have said "with a radial velocity relative to the
transceiving antenna", which would be more accurate.

Another slight problem would be that the radiation from the base station
antennae is very reduced once you get out of the horizontal plane
relative to the antenna. There's quite a high gain on the designs
normally used, giving a much tighter vertical pattern than a standard
dipole.

> However you will also interfere with a lot of base stations using the
> same channel..

Modern cellphones use channel sharing anyway. IIRC. Either CDMA or TDMA,
though I can't remember which is used where. The overall network design
should be tolerant of such errors, though. Things like not re-using the
same channel set within a biggish group of cells, for instance.

>> The proposed system means that the transmit power on the phones will be
>> minimal & under the control of the aircrew. They could also potentially
>> transmit a "System not working" signal to stop phones from transmitting
>> at dangerous points of the flight.
>>
> Or if it gets too noisy)

That'll not be the crew deciding that. After all, each person yammering
is a revenue earner for the carrier :-)

--
Tciao for Now!

John.

Woody wrote:

>> The ones fitted are properly screened.
>
>
> I assume you mean the aircraft (electronics) has proper screening? Why
> screen a mobile - it is designed to radiate?
>
Aircraft electronics is *very* well shielded at the point of origin of
any potential interference, (Things like ferrite beads on all leads
passing through the casing, properly bonded joints where metal plates
join for access plates & so on)& any antennae are shielded from internal
interference by being on the outside of the metal fuselage, usually as
far away as possible from interference generation on the manufacturer's
fitted equipment.

To get the type approval for the phones currently used in aircraft cost
a fortune, & the test program for the new cellphone units is still in
progress with a budget of millions of pounds so far. Flight testing
using a 747 isn't cheap, & separate approval has to be given for every
individual aircraft design. The new airbus designs are going to be even
harder to certify, as they use a non-conducting fuselage material.

Non type-approved transmitters, transmitting variable frequencies at
varying power from random locations in & around the airframe are a
*very* hard to shield effectively from, & there are limits imposed by
weight considerations. It's easier & cheaper, not to mention a lot safer
just to ban them altogether. There are a number of recorded incidents of
aircraft having to miss a landing & go around, with all the risks & cost
that involves, due to somebody making a cellphone call while the plane
was on final approach.

> Having said that I read recently that mp3 players generate many times
> more RFI than either a mobile phone or a laptop, although I don't own a
> mp3 player so I can't test the validity.
>
It would depend enormously on the design. I've got one that's built in
what amounts to a faraday cage, with a metallic coating on the inside of
the case, I've got another with no shielding, just the plastic case.

Mobile phones & laptops are more expensive units, so I would think less
corners are cut during design & manufacture. MP3 players run their
processor more slowly, so the interference would occur starting lower in
the spectrum than mobile phones & laptops, with closer spacing of the
harmonics. On the other side of the problem is the fact that MP3 players
use the lowest possible power consumption processors available, while
mobiles & laptops use the circuits that give the best results with
reasonable power consumption, so there's more power being switched than
in an MP3 player.

There are tests which they're all supposed to pass regarding RFI
generation to get approval for sale in various territories, but how many
of the cheaper units are even tested, or would pass if they were is a
moot point. The approval mark is very easily reproduced for a casual
buyer/ non-suspicious customs officer, especially if there is a decent
quality forged certificate of compliance with the shipment.

I've not got the gear to check properly for myself, but I note that
neither of the MP3 players or the laptop I'm typing on interfere with
the FM receiver I'm listening to at the moment, but the GPRS datacard in
the laptop sometimes does, even when it's just changing cells.

Toss a coin, would you, please. ;-)

--
Tciao for Now!

John.

On Sat, 8 Dec 2007 11:30:39 +0000, tony sayer <tony@bancom.co.uk>
wrote:

>No give them their due the aircraft environment is a very sensitive one
>and is very safety conscious. If there was the slightest risk then they
>should not be allowed but its taken some time to get that far.

Given that just about every flight these days has one or two mobiles
that their owner has forgotten to turn off (I've done it), and that we
haven't heard of any accident relating to one, I think you can be
reasonably sure they aren't a big risk.

Neil

--
Neil Williams
Put my first name before the at to reply.

"Neil Williams" <wensleydale@pacersplace.org.uk> wrote in
message news:475b0e54.633337741@news.individual.net
: : On Sat, 8 Dec 2007 11:30:39 +0000, tony sayer
: : <tony@bancom.co.uk> wrote:
: :
: : : No give them their due the aircraft environment is a
: : : very sensitive one and is very safety conscious. If
: : : there was the slightest risk then they should not be
: : : allowed but its taken some time to get that far.
: :
: : Given that just about every flight these days has one
: : or two mobiles that their owner has forgotten to turn
: : off (I've done it), and that we haven't heard of any
: : accident relating to one, I think you can be reasonably
: : sure they aren't a big risk.

How do you forget to turn it off once the flight crew have told you to do
so before takeoff..?

Ivor

On Sat, 8 Dec 2007 22:41:01 -0000, "Ivor Jones"
<ivor@despammed.invalid> wrote:

>How do you forget to turn it off once the flight crew have told you to do
>so before takeoff..?

Because I normally put all my electrical gubbins in the side of my
carry-on bag in order to speed passage through security[1], and
because the seats are so damn narrow it tends to stay there for the
flight rather than going back in my pocket.

Before putting it in said bag, I turn off said electrical gubbins.
However, on one occasion I forgot. The bag is shoved up in the
overhead by the time the above announcement is made, so a quick check
isn't practical if I'm in a window seat (which is my usual choice), so
I would rely on my turn-off-before-putting-in-bag ritual, which worked
every time but one.

I am by no means the only one who's forgotten, though. My guess is
that at least one on any given 737-sized flight is on.

[1] I'm thinking here specifically of Schiphol, where security is at
the gate, and thus I'm not likely to want or need use of said
electrical gubbins between security and the plane as this is normally
a period of no more than about 5-10 minutes.

Neil

--
Neil Williams
Put my first name before the at to reply.

In article <475b0e54.633337741@news.individual.net>, Neil Williams
<wensleydale@pacersplace.org.uk> scribeth thus
>On Sat, 8 Dec 2007 11:30:39 +0000, tony sayer <tony@bancom.co.uk>
>wrote:
>
>>No give them their due the aircraft environment is a very sensitive one
>>and is very safety conscious. If there was the slightest risk then they
>>should not be allowed but its taken some time to get that far.
>
>Given that just about every flight these days has one or two mobiles
>that their owner has forgotten to turn off (I've done it), and that we
>haven't heard of any accident relating to one, I think you can be
>reasonably sure they aren't a big risk.
>

No not if their not being used. Yes they do have the odd exchange with
their net from time to time but a few short duration bursts?..

Aviation has an excellent safety record, lets keep it that way)
>Neil
>

--
Tony Sayer

On Sun, 9 Dec 2007 13:21:26 +0000, tony sayer <tony@bancom.co.uk>
wrote:

>No not if their not being used. Yes they do have the odd exchange with
>their net from time to time but a few short duration bursts?..

If they don't have a signal, they attempt to find one using full power
tranmsission a lot more often than they "ping" the network if they do
see one.

Neil

--
Neil Williams
Put my first name before the at to reply.

Neil Williams wrote:
> On Sun, 9 Dec 2007 13:21:26 +0000, tony sayer <tony@bancom.co.uk>
> wrote:
>
>> No not if their not being used. Yes they do have the odd exchange with
>> their net from time to time but a few short duration bursts?..
>
> If they don't have a signal, they attempt to find one using full power
> tranmsission a lot more often than they "ping" the network if they do
> see one.

You do not "find" a network by transmitting you find one by receiving -
scanning several channels. Only when you have found one do you transmit.

--
Adrian Kennard, on his Mac...
Andrews & Arnold Ltd. Communications specialists. www.aaisp.net.uk
New UK Wide 03 phone numbers available now.

On Dec 9, 1:21 pm, tony sayer <t...@bancom.co.uk> wrote:
> In article <475b0e54.633337...@news.individual.net>, Neil Williams
> <wensleyd...@pacersplace.org.uk> scribeth thus
>
> >On Sat, 8 Dec 2007 11:30:39 +0000, tony sayer <t...@bancom.co.uk>
> >wrote:
>
> >>No give them their due the aircraft environment is a very sensitive one
> >>and is very safety conscious. If there was the slightest risk then they
> >>should not be allowed but its taken some time to get that far.
>
> >Given that just about every flight these days has one or two mobiles
> >that their owner has forgotten to turn off (I've done it), and that we
> >haven't heard of any accident relating to one, I think you can be
> >reasonably sure they aren't a big risk.
>
> No not if their not being used. Yes they do have the odd exchange with
> their net from time to time but a few short duration bursts?..
>
> Aviation has an excellent safety record, lets keep it that way)
>
> >Neil
>
> --
> Tony Sayer

Aircraft systems are well shielded but I have personally witnessed the
effect a mobile phone can have when used within 30 feet of a live
cockpit.
1. Radio signals between the controller and the crew are subjected to
a constant rythmic bleeping accompanied by a steady buzz.
2. On a Jersey European BAE 146 in 2000 (now Flybe) with old style
cockpit using dials. Instrument lights flickered and some dials had
indicators moving rapidly from side to side. Not by a great deal but
it was described as distracting.
3. On a much newer CRJ 50 seater using a modern "glass" cockpit the
effect was not noticeable but the radio interference remained.

The basic fact is nobody can guarantee that every type of mobile phone
electronic signature will not in some way affect the many different
types of system on an aircraft. With hundreds of different types of
phone and more appearing almost weekly, who will take responsibility
for EMC testing them against every type of passenger carrying
aircraft? Easier not to take the risk.

Neil Williams wrote:

> If they don't have a signal, they attempt to find one using full power
> tranmsission a lot more often than they "ping" the network if they do
> see one.

Not true. If they don't see a signal, they don't transmit at all.

"Gavin" <gavin@mindless.com> wrote in message
news:dahun354lhemouuc0ffdmkdt8end7molb0@4ax.com...
> On Fri, 04 Jan 2008 21:46:39 +0000, Iain <no-one@hairydog.co.uk>
> wrote:
>
>>Neil Williams wrote:
>>
>>> If they don't have a signal, they attempt to find one using full power
>>> tranmsission a lot more often than they "ping" the network if they do
>>> see one.
>>
>>Not true. If they don't see a signal, they don't transmit at all.
>
> not quite, they'll periodically poll to see if a network is there, and
> if there is one if it's one the phone can use.
>
> Otherwise when you went out of coverage you'd never go back in
> coverage when the network came back short of power cycling the phone.

Poll implies that they transmit, I thought the phone would scan around
looking for a suitable network and then try to register on the strongest
signal.

I also thought that when out of range the interval between the phone doing a
search got longer but it would keep trying. Cycling the phone can just
speed things up.

One problem with jamming or screening that if the phone receives a signal
from a base station then it will go onto its highest power to try to
register and stay registered. So any interference could be worst that it
would be otherwise.

MB

On Sat, 05 Jan 2008 08:50:47 GMT, Gavin <gavin@mindless.com> wrote:

>On Fri, 04 Jan 2008 21:46:39 +0000, Iain <no-one@hairydog.co.uk>
>wrote:
>
>>Neil Williams wrote:
>>
>>> If they don't have a signal, they attempt to find one using full power
>>> tranmsission a lot more often than they "ping" the network if they do
>>> see one.
>>
>>Not true. If they don't see a signal, they don't transmit at all.
>
>not quite, they'll periodically poll to see if a network is there, and
>if there is one if it's one the phone can use.
>
>Otherwise when you went out of coverage you'd never go back in
>coverage when the network came back short of power cycling the phone.

But do they actually need to transmit a signal in order to detect the
presence of a network? Couldn't the phone just periodically scan for
received signals and only transmit when attempting to register on a
network?

Chris

On Sat, 5 Jan 2008 10:46:12 -0000, "MB" <mb@invalid.invalid> wrote:

>
>"Gavin" <gavin@mindless.com> wrote in message
>news:dahun354lhemouuc0ffdmkdt8end7molb0@4ax.com.. .
>> On Fri, 04 Jan 2008 21:46:39 +0000, Iain <no-one@hairydog.co.uk>
>> wrote:
>>
>>>Neil Williams wrote:
>>>
>>>> If they don't have a signal, they attempt to find one using full power
>>>> tranmsission a lot more often than they "ping" the network if they do
>>>> see one.
>>>
>>>Not true. If they don't see a signal, they don't transmit at all.
>>
>> not quite, they'll periodically poll to see if a network is there, and
>> if there is one if it's one the phone can use.
>>
>> Otherwise when you went out of coverage you'd never go back in
>> coverage when the network came back short of power cycling the phone.
>
>Poll implies that they transmit, I thought the phone would scan around
>looking for a suitable network and then try to register on the strongest
>signal.
>
>I also thought that when out of range the interval between the phone doing a
>search got longer but it would keep trying. Cycling the phone can just
>speed things up.
>
>One problem with jamming or screening that if the phone receives a signal
>from a base station then it will go onto its highest power to try to
>register and stay registered. So any interference could be worst that it
>would be otherwise.
>
Even if the phone sat in what amounted to "listen only" mode it would
still have to transmit to an available base station at intervals to
let the system know that it was active otherwise the system would
assume it was no longer active or within range.

On 2008-01-05, MB <mb@invalid.invalid> wrote:
>
> One problem with jamming or screening that if the phone receives a signal
> from a base station then it will go onto its highest power to try to
> register and stay registered. So any interference could be worst that it
> would be otherwise.

As long as the interference lowers the SNR sufficiently, the phone won't
be able to hear the base station anyway.

--
David Taylor

On 2008-01-05, Charles Ellson <charles@ellson.demon.co.uk> wrote:
>
> Even if the phone sat in what amounted to "listen only" mode it would
> still have to transmit to an available base station at intervals to
> let the system know that it was active otherwise the system would
> assume it was no longer active or within range.

When the phone can't hear a base station there is nothing
to transmit to!

--
David Taylor

On Sat, 5 Jan 2008 21:33:24 +0000 (UTC), David Taylor
<davidt-news@yadt.co.uk> wrote:

>On 2008-01-05, Charles Ellson <charles@ellson.demon.co.uk> wrote:
>>
>> Even if the phone sat in what amounted to "listen only" mode it would
>> still have to transmit to an available base station at intervals to
>> let the system know that it was active otherwise the system would
>> assume it was no longer active or within range.
>
>When the phone can't hear a base station there is nothing
>to transmit to!
>
If you unsnip the immediately preceding paragraph you'll find the
subject was a phone within range of a base station. I was merely
indicating that "conversation" between the 'phone and base station
continues at intervals after the initial connection is established.